In a small saucepan combine brown sugar, molasses, water, rosemary and cinnamon sticks. Bring to a boil, stirring to dissolve sugar. Simmer 3-5 minutes. Remove from heat and allow to cool.
Working one orange slice at a time, sprinkle with a teaspoon of sugar and use a culinary torch to melt and caramelize the sugar. Set aside.
In a cocktail shaker add bourbon, orange juice, bitters, simple syrup and ice. Shake to combine and to chill. Pour over a large cocktail ice cube, top with club soda.
Garnish with a spring of rosemary, a cinnamon stick and an orange slice.